The retrovirus designated “human immunodeficiency virus” or “HIV” is the etiological agent of a complex disease that progressively destroys the immune system. The disease is known as acquired immune deficiency syndrome or AIDS. AIDS and other HIV-caused diseases are difficult to treat due to the ability of HIV to rapidly replicate, mutate and acquire resistance to drugs. To attempt to slow the spread of the virus after infection, treatment of AIDS and other HIV-caused diseases has focused on inhibiting HIV replication.
Since HIV is a retrovirus, and thus, encodes a positive-sense RNA strand, its mechanism of replication is based on the conversion of viral RNA to viral DNA, and subsequent insertion of the viral DNA into the host cell genome. HIV replication relies on three constitutive HIV encoded enzymes: reverse transcriptase (RT), protease and integrase.
Upon infection with HIV, the retroviral core particles bind to specific cellular receptors and gain entry into the host cell cytoplasm. Once inside the cytoplasm, viral RT catalyzes the reverse transcription of viral ssRNA to form viral RNA-DNA hybrids. The RNA strand from the hybrid is then partially degraded and a second DNA strand is synthesized resulting in viral dsDNA. Integrase, aided by viral and cellular proteins, then transports the viral dsDNA into the host cell nucleus as a component of the pre-integration complex (PIC). In addition, integrase provides the permanent attachment, i.e., integration, of the viral dsDNA to the host cell genome which, in turn, provides viral access to the host cellular machinery for gene expression. Following integration, transcription and translation produce viral precursor proteins. Protease then cleaves the viral precursor proteins into viral proteins which, after additional processing, are released from the host cell as newly infectious HIV particles.
A key step in HIV replication, insertion of the viral dsDNA into the host cell genome, is believed to be mediated by integrase in at least three, and possibly, four, steps: (1) assembly of proviral DNA; (2) 3′-end processing causing assembly of the PIC; (3) 3′-end joining or DNA strand transfer, i.e., integration; and (4) gap filling, a repair function. See, e.g., Goldgur, Y. et al., PNAS 96(23): 13040–13043 (November 1999); Sayasith, K. et al., Expert Opin. Ther. Targets 5(4): 443–464 (2001); Young, S. D., Curr. Opin. Drug Disc. & Devel. 4(4): 402–410 (2001); Wai, J. S. et al., J. Med. Chem. 43(26): 4923–4926 (2000); Debyser, Z. et al., Assays for the Evaluation of HIV-1 Integrase Inhibitors, from Methods in Molecular Biology 160: 139–155, Schein, C. H. (ed.), Humana Press Inc., Totowa, N. J. (2001); and Hazuda, D. et al., Drug Design and Disc. 13:17–24 (1997).
In the first step, integrase forms a stable complex with the viral long terminal repeat (LTR) regions. Once the complex is formed, integrase then performs an endonucleolytic processing step whereby the terminal GT dinucleotides of the 3′ ends (immediately downstream from a conserved CA dinucleotide) of both DNA strands are cleaved. The processed DNA/integrase complex (the PIC) then translocates across the nuclear membrane. Once inside the host cell nucleus, integrase performs the third step, 3′-end joining, whereby a cut is made in the host cell DNA to covalently join the processed 3′-ends of the viral processed DNA during two transesterification reactions. In the fourth step, cellular enzymes repair the resultant gap at the site of viral DNA insertion. The enzymes, if any, employed in the repair process have not been accurately identified. Sayasith, K. et al., Expert Opin. Ther. Targets 5(4): 443–464 (2001). Thus, the role that integrase plays in the gap filling function is not known.
It is clear that the role that integrase plays in the integration of the viral DNA into the host cell genome occurs through well-ordered reactions directed by various viral and cellular factors. This knowledge provides a variety of opportunities to block the essential step of integration (and the essential enzyme integrase) in the HIV life cycle.
Currently, AIDS and other HIV-caused disease are treated with an “HIV cocktail” containing multiple drugs including RT and protease inhibitors. However, numerous side effects and the rapid emergence of drug resistance limit the ability of the RT and protease inhibitors to safely and effectively treat AIDS and other HIV-caused diseases. In view of the shortcomings of RT and protease inhibitors, there is a need for another mechanism through which HIV replication can be inhibited. Integration, and thus integrase, a virally encoded enzyme with no mammalian counterpart, is a logical alternative. See, e.g., Wai, J. S. et al., J. Med. Chem. 43:4923–4926 (2000); Grobler, J. et al., PNAS 99: 6661–6666 (2002); Pais, G. C. G. et al., J. Med. Chem. 45: 3184–3194 (2002); Young, S. D., Curr. Opin. Drug Disc. & Devel. 4(4): 402–410 (2001); Godwin, C. G. et al., J. Med. Chem. 45: 3184–3194 (2002); Young, S. D. et al., “L-870,810: Discovery of a Potent HIV Integrase Inhibitor with Potential Clinical Utility,” Poster presented at the XIV International AIDS Conference, Barcelona (Jul. 7–12, 2002); and WO 02/070491.
It has been suggested that for an integrase inhibitor to function, it should inhibit the strand transfer integrase function. See, e.g., Young, S. D., Curr. Opin. Drug Disc. & Devel. 4(4): 402–410 (2001). Thus, there is a need for HIV inhibitors, specifically, integrase inhibitors, and, more specifically, strand transfer inhibitors, to treat AIDS and other HIV-caused diseases. The inventive agents disclosed herein are novel, potent and selective HIV-integrase inhibitors, and, more specifically, strand transfer inhibitors, with high antiviral activity and low toxicity.
The references made to published documents throughout this application more fully describe the state of the art to which this invention pertains. The disclosures of these references are hereby incorporated by reference in their entireties.